1. Field of the Invention
The present invention relates to an improved cutting blade for a shredder, particularly to a round undulating blade that is integrally formed by punching a sheet metal in a punching die or a round undulating blade module that is integrally formed by die-casting.
2. Background Information
With increased privacy concerns, shredders have become an integral part in both homes and businesses. The conventional shredders for cutting paper use a plurality of cutting blades and spacers engaging over a rotary cutter shaft, and the shearing force that two parallel and opposite rotary cutter shafts produce for transferring and cutting the paper-to-be-cut along a longitudinal direction into strips. Shredders typically fall into one of two types: the strip-cut shredders and crosscut shredders, according to the machine cutting style. The strip-cut shredders arrange cutting blades on the rotating cutter shafts in a manner to cut paper longitudinally to form strips. The crosscut shredders include blades with more than one cutting edge part, and each cutter is disposed in a helix fashion along the rotary cutter shaft for first cutting paper along a longitudinal direction into strips and then cutting paper along a horizontal direction into approximate 4 mm by 40 mm paper chips.
By referring to the assembled perspective view of a conventional blade illustrated in FIG. 1 and a planar view showing the operation of the conventional blade in FIG. 2, the conventional blade is made by punching a sheet metal having a thickness of approximately 2 mm into a circular blade by a die. The blade includes a polygonal central hole A1 through which a rotary shaft may pass. The blade also includes cutting edges A2 that are spaced in about 120 degrees apart around the periphery. As shown, when two blades are arranged on the rotary shafts S in a back-to-back manner to combine into a set of blades A, the cutting edges of the two blades assume a V-like edge A3. The opposite rotary shafts S′ space the two blades apart by space rings (not shown) in a face-to-face manner to form a set of blade A′. When the paper to be cut passes through the two reverse rotary shafts S, S′, the opposing rotation of the periphery of the blades, that is, flanks A4 and flanks A4, will cut the paper like scissors. The opposing rotation of cutting edges A2 and the opposite flanks A4 will then cut the paper along a horizontal direction into 4 mm.×0.40 mm paper chips.
During operating of the conventional blades, to ensure smooth cutting of the paper along the horizontal direction, sharp blades with proper orientations are needed. However, because the blades are formed by a punch die, the die wear that increases with the time will reduce sharpness of the blade edges, which does not improve until replacing the die, to result in inconsistent quality. To ensure quality of the blades, it is necessary to shorten the service term of the die, which results in increment of the cost. In addition, in the conventional blades, the thickness of the blade is the same as the width of paper to be cut. To ensure the strength of blades while cutting along the horizontal direction, the blades cannot be too thin, or else the blades tend to deform or fracture. Such a limitation attributes to the high material cost, which is less competitive as compared to the current market price. In addition, because the thickness of the conventional blades is the same as the width of the paper to be cut, and because the location of the width define the horizontal cutting points, the narrower width of cross-section is, the smaller output power is needed to cut along the horizontal direction. In other words, the motor can supply a minimum power for cutting along the horizontal direction, that is, to reduce the power consumed by the motor. But, because of the width of the paper cut by the conventional blades is 4 mm, the motor needs to output higher power to drive the blades and flanks moving in opposing directions to cut the paper along the horizontal direction smoothly.
From the preceding descriptions, it is apparent that the devices currently being used have significant disadvantages and/or limitations. Thus, important aspects of the technology used in the field of invention remain amenable to useful refinement.